notroubleclubber

My bro has an old alfa 147. The battery went flat so went to jump start it yesterday but it wont fire. It turns over but doesnt start. There is a key icon flashing when trying to turn it over so im guessing the immoibliser has cut in. He has a fob but the battery on that is dead and normally he doesnt use it and just uses the red key he has got to get in and drive it. Is there a way to turn off the immobiliser just with the key?

Ive tried locking and unlocking it with the key but still no difference.